Nuclear Receptor Coactivators GRIP1, CoCoA and Flil

描述（由申请人提供）：激素激活的核受体（NR）结合靶基因启动子并招募辅激活子复合物来帮助激活转录。p160共激活因子复合体由一个直接与活化的nr结合的p160蛋白和几个次级共激活因子组成。我们的总体策略是表征共激活因子的功能域，并寻找与其激活域结合并在共激活因子信号通路中介导下游事件的蛋白质。通过重复应用这一过程，我们将在染色质或基础转录机制中找到p160共激活子的最终目标。p160蛋白先前被证明具有两个用于信号传输的c端激活域：AD1结合CBP/p300，而AD2结合CARM1。我们最近在p160共激活因子（AD3）的n端区域发现了一个新的激活域，并鉴定了两种结合p160 n端并与p160蛋白协同合作作为nr共激活因子的蛋白：coiledcoil Coactivator （CoCoA）和Flightless I （Flil）。在这里，我们将确定每种蛋白质与其他NR共激活因子合作并促进NR转录激活的机制。我们将通过定义它们与NRs、p160共激活子和/或其他已知蛋白质相互作用伙伴的相互作用位点来定义CoCoA和Flil的功能子结构域。我们还将定义它们的激活域，这些激活域用于将激活信号传递给转录机制，并识别与激活域结合的蛋白质，从而在激活信号通路中处于下游。CoCoA和Flil作为辅助激活因子与其他类型的转录因子的参与也将被研究。最后，我们将研究A549细胞系中多种类固醇激素调控的启动子（一些激素可诱导和一些激素可抑制）对CoCoA和Flil及其不同功能域的不同需求，探讨协同激活子功能机制与启动子结构的关系。

DESCRIPTION (provided by applicant): Hormone-activated nuclear receptors (NR) bind to target gene promoters and recruit complexes of coactivators to help activate transcription. The p160 coactivator complex consists of a p160 protein, which binds directly to activated NRs, and several secondary coactivators. Our global strategy is to characterize the functional domains of coactivators and search for proteins that bind to their activation domains and mediate downstream events in the coactivator signaling pathway. By reiterative application of this process, we will find the ultimate targets of the p160 coactivators in the chromatin or basal transcription machinery. The p160 proteins were previously shown to have two C-terminal activation domains for signal transmission: AD1 binds CBP/p300, while AD2 binds CARM1. We recently identified a new activation domain in the N-terminal region of p160 coactivators (AD3) and identified two proteins which bind to the p160 N-terminus and cooperate synergistically with p160 proteins as coactivators for NRs: Coiled-coil Coactivator (CoCoA) and Flightless I (Flil). Here, we will determine the mechanisms by which each of these proteins cooperates with other NR coactivators and contributes to transcriptional activation by NRs. We will define the functional subdomains of CoCoA and Flil by defining their sites of interaction with NRs, p160 coactivators, and/or other known protein interaction partners. We will also define their activation domains, which are used to transmit the activating signal to the transcription machinery, and identify proteins that bind to the activation domains and are thus downstream in the activation signaling pathway. The involvement of CoCoA and Flil as coactivators with other classes of transcription factors will also be investigated. Finally, we will study the variable requirements for CoCoA and Flil and their various functional domains on multiple steroid hormone-regulated promoters (some hormone inducible and some hormone repressible) in the A549 cell line to investigate the relationship between mechanism of coactivator function and promoter architecture.